Wastewater purification with nanoparticle-treated bed

ABSTRACT

Nanoparticle-treated particle packs, such as sand beds, may effectively filter and purify liquids such as waste water. When tiny contaminant particles in waste water flow through the particle pack, the nanoparticles will capture and hold the tiny contaminant particles within the pack due to the nanoparticles&#39; surface forces, including, but not necessarily limited to van der Waals and electrostatic forces. Coating agents may help apply the nanoparticles to the particle surfaces in the filter beds or packs.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 14/332,815, filed Jul. 16, 2014 and issued on Jan. 10, 2017 asU.S. Pat. No. 9,540,251; which is a divisional application of U.S.patent application Ser. No. 13/542,887, filed Jul. 6, 2012 and issued onAug. 26, 2014 as U.S. Pat. No. 8,815,089; which is a divisionalapplication of U.S. patent application Ser. No. 12/111,361, filed Apr.29, 2008 and issued on Jul. 24, 2012 as U.S. Pat. No. 8,226,830; all ofwhich are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to methods and compositions for removingcontaminants from liquids, such as wastewater, and more particularlyrelates, in one non-limiting embodiment, to methods and compositions forremoving contaminants from wastewater using particle packs that havebeen treated with nano-sized particles.

BACKGROUND

Many methods and processes are known to clean, purify, clarify andotherwise treat fluids for proper disposal, consumption, use, and otherneeds. These methods include, but are not necessarily limited to,centrifugation and filtration to remove particulates, chemicaltreatments to sterilize water, distillation to purify liquids, decantingto separate two phases of fluids, reverse osmosis to desalinate liquids,electrodialysis to desalinate liquids, pasteurization to sterilizefoodstuffs, and catalytic processes to covert undesirable reactants intouseful products. Each of these methods is well-suited for particularapplications and typically a combination of methods is used for a finalproduct.

There are many different known technologies available for thesterilization of liquid. Adsorption, chemical treatments, ozonedisinfection, and ultraviolet (UV) irradiation all perform very well forthe removal of pathogenic microbes. However, each of these technologieshas limitations, including overall efficacy, initial capital cost,operating cost, byproduct risk, necessary pre-treatment of liquid,hazardous compounds used or produced, and which thus must be properlydisposed of, and other limitations.

Although chemical methods are the most widespread in use, they have anumber of shortcomings. Such drawbacks include increasingmicrobiological adaptation to their destructive effects, safety hazardsassociated with chlorine use and storage, and environmental impact. UVis a popular treatment, but the liquid must be clear in order for it tobe effective, and it does not break down any biofilm formation; it isalso very expensive to install and operate. In industrial and municipalapplications such as water and wastewater plants, the three most widelyused methods of liquid sterilization are ozone treatment, chlorinetreatment, and UV irradiation.

Desalination of liquids is highly useful for drinking water, biologicalfluids, medicines, chemicals, petroleum and its derivatives, and manyother liquids. In addition, desalination of water would be beneficialsince less than 0.5% of the Earth's water is directly suitable for humanconsumption, agricultural, or industrial uses. Consequently,desalination is finding increasing favor to produce potable water frombrackish groundwater and seawater since it makes the other approximately99.5% of the water available. There are five basic desalination methods:thermal, reverse osmosis, electrodialysis, ion exchange, and freezing.Thermal and freezing processes remove fresh water from saline leavingbehind concentrated brine. Reverse osmosis and electrodialysis employmembranes to separate salts from fresh water. Ion exchange involvespassing salt water over resins which exchange more desirable ions forless desirable dissolved ions. Only thermal and reverse osmosisprocesses are currently commercially viable. Even so, these two methodstend to be prohibitive due to their expense.

There is always a need to develop new apparatus and methods that willhelp perform these methods and processes more cost effectively thantheir traditional counterparts. In the area of liquid purification, anytechnology that can lower the overall cost, simplify the process, andimprove efficiencies would be very advantageous. It would thus bedesirable if methods and/or structures would be devised to purifyliquids, such as wastewater, using simple methods and devices.

SUMMARY

There is provided, in one form, a method for purifying an aqueous liquidcontaining contaminant particles selected from the group consisting ofclay particles, silica particles, sediments, soil particles, miningparticles and water treatment particles. The method may includecontacting the aqueous liquid containing the contaminant particles witha particle pack having substrate particles and comparatively smallerparticulate additives and attracting the contaminant particles from theaqueous liquid to the particulate additive to purify the aqueous liquid.The substrate particles may be comparatively larger than the particulateadditive and may be or include sand, gravel, ceramic beads, glass beads,and combinations thereof. The particle pack may be at least partiallycoated with a coating agent including a carrier fluid, such as alcohol,glycol, polyol, vegetable oil, mineral oil, and combinations thereof.The particulate additives may have a mean particle size of 1000 nm orless and may be or include alkaline earth metal oxides, alkaline earthmetal hydroxides in the absence of magnesium oxide, alkali metal oxides,alkali metal hydroxides, transition metal oxides, transition metalhydroxides, post-transition metal oxides, post-transition metalhydroxides, piezoelectric crystals, pyroelectric crystals, and mixturesthereof.

There is additionally provided in another non-limiting embodiment of themethod where the substrate particles have a mean particle size of fromabout 2000 microns to about 45 microns and where the particulateadditive may range from about 1 part by weight for about 200 to about5000 parts by weight of the particle pack.

There is additionally provided in another non-limiting embodiment of themethod where the coating agent may be an oil-wetting surfactant and amineral oil, and where the particulate additives are at least partiallycoated on the substrate particles by the mineral oil.

The particulate additives, also referred to herein as nano-sizedparticles or nanoparticles (e.g. MgO and/or Mg(OH)₂, and the like),appear to fixate, bind up, or otherwise capture contaminants, such asclay and non-clay particles, including charged and non-chargedparticles. Due to at least in part to their small size, the surfaceforces (e.g. van der Waals and electrostatic forces) of thenanoparticles help them associate, group or flocculate the tinycontaminant particles together in larger collections, associations oragglomerations. Such groupings or associations help capture thecontaminants in place and keep them from moving and passing through withthe liquid, resulting in a purified liquid. In many cases, the purifyingability of the particle pack may be improved by use of nano-sizedparticulate additives that may be much smaller in size than thecontaminants.

The addition of alkaline earth metal oxides, such as magnesium oxide;alkaline earth metal hydroxides, such as calcium hydroxide; transitionmetal oxides, such as titanium oxide and zinc oxide; transition metalhydroxides; post-transition metal oxides, such as aluminum oxide;post-transition metal hydroxides; piezoelectric crystals and/orpyroelectric crystals such as ZnO and AIPO₄, to an aqueous fluid, asolvent-based fluid such as glycol, or oil-base fluid, e.g. mineral oil,may be used to treat the particle pack, such as a sand bed, which inturn is expected to purify, clarify and otherwise clean the fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph of a sand pack test apparatus for a sand packthat is untreated with nanoparticles, showing cloudy fluid simulatingwaste water at the top of the apparatus and cloudy fluid flowing fromthe apparatus at the bottom;

FIG. 2 is a more detailed photograph of the cloudy fluid simulatingwaste water at the top of the sand pack test apparatus of FIG. 1;

FIG. 3 is a is a more detailed photograph of the cloudy fluid havingpassed through the sand pack test apparatus of FIG. 1 showing that thefluid remains cloudy;

FIG. 4 is a photograph of the sand pack test apparatus for a sand packthat has been treated with nanoparticles, showing cloudy fluidsimulating waste water at the top of the apparatus and clear waterflowing from the apparatus at the bottom;

FIG. 5 is a more detailed photograph of the clear water having passedthrough the sand pack test apparatus of FIG. 4 showing that the waterhas been purified; and

FIG. 6 is a particle size distribution (PSD) of the bentonite particlesused in the simulated wastewater used in the above test apparatus,illustrating a volume weighted mean particle size of about 31.2 microns.

DETAILED DESCRIPTION

Methods and compositions of nanoparticle-treated sand beds have beendiscovered as useful to purify waste water. When tiny contaminantparticles in waste water flow through a nanoparticle-treated sand bed,the nanoparticles will capture and hold the tiny contaminant particlesin the sand bed by the nanoparticles' surface forces, including but notnecessarily limited to, van der Waals and electrostatic forces, therebyremoving them from the liquid. The contaminants or impurities mayinclude, but not necessarily be limited to, sediments, soil particles,mining particles, water treatment particles, and the like. In onenon-limiting embodiment the treated fluids are aqueous, by which ismeant they contain water; in a non-restrictive, alternative embodimentthe aqueous fluids are at least 50 weight % water, alternatively atleast 30 wt % water. The purified water may thus be used as injectionwater in underground hydrocarbon reservoirs to effectively recoverhydrocarbons, or as municipal water for continued purification for humanconsumption.

It has been discovered that nano-sized particles like magnesium oxide(MgO) may be used to remove contaminants such as clay and non-clayparticles from liquids, that is, to remove, reduce or rid them frombeing present in the fluid, such as water. Some nano-sized particles,also called nanoparticles herein, not only have high surface areascompared to their small sizes, but also have relatively high surfacecharges that permit them to associate, link or connect other particlestogether, including other charged particles, but also other non-chargedparticles. In one non-limiting embodiment, these associations orconnections between the contaminant particles and the nano-sizedparticles are due to electrical attractions and other intermolecularforces or effects.

As will be shown, laboratory tests have demonstrated that relativelysmall amounts of MgO nanoparticles can remove and eliminate dispersedclay particles. It is expected that charged and non-charged colloidalsilicas will also be removed. Other nanoparticles such as ZnO, Al₂O₃,zirconium dioxide (ZrO₂), TiO₂, cobalt (II) oxide (CoO), nickel (II)oxide (NiO), and pyroelectric and piezoelectric crystals may also beused in the methods and compositions herein.

The nanoparticles may be applied directly to and placed on and in aparticulate pack, such as a sand bed, typically by contacting the packor bed with a fluid in which the nanoparticles are suspended. In oneembodiment, a mixture of a coating agent and nanoparticles at leastpartially coat the selected sand bed or other porous media (substrateparticles). If sand or gravel is at least partially coated with thecoating agent and the nanoparticles, then the contaminants andimpurities may be removed from the fluid, e.g. wastewater, and may beeliminated or suppressed thereby purifying the fluid.

The coating agent may be a carrier fluid that includes, but is notnecessarily limited to, an alcohol, glycol, polyol, vegetable oil, fishoil and combinations thereof. One particularly suitable carrier fluidmay be monopropylene glycol. Alternatively, suitable coating agentsinclude, but are not necessarily limited to, mineral oil or otherhydrocarbon that accomplishes the purposes of the methods andcompositions described herein. Specific, non-limiting examples ofsuitable mineral oils include ConocoPhillips PURE PERFORMANCE® Base OilsII or III, such as 225N, 600N, ULTRA-S™ 3 and ULTRA-S™ 8; PenrecoDRAKEOL® oils, such as DRAKEOL® 21, DRAKEOL® 35 and DRAKEOL® 600; andExxonMobil Chemical mineral oils, such as EXXSOL® D80 and ISOPAR® Moils. It is expected that a filtering or purification product willinclude nanoparticles in the coating agent oil, for instance about 15 wt% nano-sized MgO particles in the Drakeol® 600 mineral oil. It has beendiscovered that during mixing with the particles of the pack or bed, thenanoparticles in oil, glycol, or other carrier will plate out on or atleast partially coat the substrate particles. How much coating of thesubstrate particles that occurs is concentration dependant, based onboth the amount of particles, e.g. sand, used and the amount ofnanoparticles used. In a non-limiting example, the carrier fluid mayadditionally have a surfactant present, such as an oil-wettingsurfactant like sorbitan monooleate (i.e. SPAN 80 from Uniqema), toimprove and/or enhance the oil-wetting of the pack or bed substrateparticles by the nanoparticles. In another non-limiting example, thepresence of a surfactant may preferentially reduce the thickness of theDRAKEOL® 600 mineral oil layer on the sand pack particles. Reduced oillayer thickness may enhance nanoparticle exposure on the sand or ceramicparticles. Use of lower viscosity mineral oils, such as DRAKEOL® 15,DRAKEOL® 18 or EXXSOL® D80 can also be used to reduce oil layerthickness. Other agents besides SPAN 80 may be employed to optimize theoil coating or wetting or thickness on the sand pack or ceramic bedparticles, agents such as: sorbitan esters, ethoxylated sorbitan esters,ethoxylated alcohols, ethoxylated alkyl-phenols, alkyl-dicarboxylics,sulfosuccinates, phospholipids, alkyl-amines, quaternary amines,alkyl-siloxanes, and the like. It is not necessary that a resin be usedas a coating agent or binder, and in one non-limiting embodiment, noresin is used.

It is theorized that the nanoparticles remain on the particles of theparticle pack primarily by electrostatic and other charges between thenanoparticle and particle surfaces, however, other attractions orcoupling forces may exist to initially and over the long-term keep thenanoparticles coated on the pack or bed substrate particles. Theinventors do not want to be limited to any particular theory. It issuspected that in most conditions the carrier fluid only assists theinitial coating process of the nanoparticles on to the substrateparticles of the pack or bed. However, other agents may be added to thecarrier fluid that may further enhance the initial and/or long-termnanoparticle attraction to the sand (silica or quartz or feldspars),glass, ceramic and the like particles.

Nano-sized particles of alkaline earth metal oxides, alkaline earthmetal hydroxides, alkali metal oxides, alkali metal hydroxides,transition metal oxides, transition metal hydroxides, post-transitionmetal oxides, and post-transition metal hydroxides, piezoelectriccrystals, pyroelectric crystals, and mixtures thereof have beendiscovered to have particular advantages for filtering out and bindingup impurities and contaminants, thereby purifying fluids.

Magnesium oxide particles and powders have been suitably used to filterfluids herein. However, it will be appreciated that although MgOparticles are noted throughout the description herein as onerepresentative or suitable type of alkaline earth metal oxide and/oralkaline earth metal hydroxide particle, other alkaline earth metaloxides and/or alkaline earth metal hydroxides and/or transition metaloxides, transition metal hydroxides, post-transition metal oxides, andpost-transition metal hydroxides, piezoelectric crystals, pyroelectriccrystals, may be used in the methods and compositions herein.Additionally, the alkali metal oxides and/or hydroxides may be usedalone or in combination with the alkaline earth metal oxides andhydroxides, and/or together with one or more transition metal oxide,transition metal hydroxide, post-transition metal oxide, post-transitionmetal hydroxide, piezoelectric crystal, and pyroelectric crystal.

By “post-transition metal” is meant one or more of aluminum, gallium,indium, tin, thallium, lead and bismuth. In another non-limitingembodiment herein, the nano-sized particles are oxides and hydroxides ofelements of Groups IA, IIA, IVA, IIB and IIIB of the previous IUPACAmerican Group notation. These elements include, but are not necessarilylimited to, Na, K, Mg, Ca, Ti, Zn and/or Al. In one non-limitingembodiment, there is an absence of alumina (aluminum oxide) and/oraluminum hydroxide from the suitable nanoparticles.

The nano-sized particulate additives herein may also be piezoelectriccrystal particles (which include pyroelectric crystal particles).Pyroelectric crystals generate electrical charges when heated andpiezoelectric crystals generate electrical charges when squeezed,compressed or pressed.

In one non-limiting embodiment, specific suitable piezoelectric crystalparticles may include, but are not necessarily limited to, ZnO,berlinite (AlPO₄), lithium tantalate (LiTaO₃), gallium orthophosphate(GaPO₄), BaTiO₃, SrTiO₃, PbZrTiO3, KNbO₃, LiNbO₃, LiTaO₃, BiFeO₃, sodiumtungstate, Ba₂NaNb₅O₅, Pb₂KNb₅O₁₅, potassium sodium tartrate,tourmaline, topaz and mixtures thereof. The total pyroelectriccoefficient of ZnO is −9.4 C/m²K. ZnO and these other crystals aregenerally not water soluble.

In one non-restrictive explanation, when the particle pack or sand bedcontains very small pyroelectric crystals, such as nano-sized ZnO, thepyroelectric crystals may be heated and/or pressed and high surfacecharges are generated. The surface charges may be generated or producedif the fluid is under pressure. These surface charges permit the crystalparticles to associate, link, connect or otherwise relate the impuritiesand contaminants together to bind them together and also to thesurrounding particle pack or sand surfaces. The association or relationof the impurities or contaminants is thought to be very roughlyanalogous to the crosslinking of polymer molecules by crosslinkers, inone non-limiting image.

In another non-limiting embodiment, the nano-sized solid particulatesand powders useful herein include, but are not necessarily limited to,alkaline earth metal oxides or alkaline earth metal hydroxides, ormixtures thereof. In one non-limiting embodiment, the alkaline earthmetal in these additives may include, but are not necessarily limitedto, magnesium, calcium, barium, strontium, combinations thereof and thelike. In one non-limiting embodiment, MgO may be obtained in high purityof at least 95 wt %, where the balance may be impurities such asMg(OH)₂, CaO, Ca(OH)₂, SiO₂, Al₂O₃, and the like.

In an additional non-restrictive version, the particle size of theadditives and agents ranges between about 4 nanometers independently upto about 1000 nanometers. In another non-limiting embodiment, theparticle size ranges between about 4 nanometers independently up toabout 500 nanometers. In another non-restrictive version, the particlesmay have a mean particle size of about 250 nm or less, alternativelyabout 100 nm or less, and in another possible version about 50 nm orless, alternatively 40 nm or less.

The amount of nano-sized particles in the sand or ceramic bed packmaterial may be from about 1 pound of nanoparticles for about 200 poundsto 5000 pounds of sand. It will be appreciated that any other unit ofweight may be used, for instance, from about 1 gram of nanoparticles forabout 200 grams to 5000 grams of sand. In an alternate embodiment, thenanoparticles are present in an amount of from about 1 part by weightnanoparticles to about 1000 independently to about 2000 parts sand orceramic pack material.

The nano-sized particles herein may be added to water, a glycol,alcohol, polyol, olefin, vegetable oil, fish oil, or mineral oil, ormixtures of these, as the carrier fluid—a combination which also servesto initially coat, or at least partially coat, the nanoparticles to thesand or ceramic. In another non-limiting embodiment, the nano-sizedparticles coated on ceramic particles or sand herein may be added to anaqueous fluid during a treatment.

The sand, ceramic, glass or other substrate particles of the pack or bedmay have a mean particle size of the particles of from about 10 mesh toabout 325 mesh (about 2000 microns to about 45 microns), in onenon-limiting embodiment. Alternatively, the substrate particles mayrange in size from about 20 mesh independently to about 200 mesh (fromabout 850 microns independently to about 75 microns). The substrateparticle size range may be wide, such as from about 40 mesh to about 200mesh (from about 425 microns to about 250 microns), or the particle sizerange may be relatively narrow, such as from about 20 mesh to about 40mesh (from about 850 microns to about 425 microns).

In another non-limiting version, the nanoparticles may be coated onceramic or sand at a supplier facility before use in a fluid purifyingtreatment. In a different non-limiting embodiment, a select portion ofthe sand or ceramic may be lightly coated with carrier fluid containingnanoparticles during a treatment, or before a fluid purification orclarification treatment. It has been discovered that PG-coatednanoparticles tend to be attached to, adhered to, or bound to theceramic particles or sand.

Laboratory tests have shown that 35 nanometer MgO particles andmonopropylene glycol (PG) coated on a 20/40 mesh (850/425 micron) sandpack can successfully remove contaminants from wastewater.

While the methods and structures herein are sometimes describedtypically herein as having use in wastewater fluids, such as those frompaper processing, the compositions and methods are also expected to beuseful in oil field recovery, e.g. produced formation water, exhausteddrilling muds, metal-working, agricultural operations, miningoperations, environmental remediation operations, waste disposaloperations, cleaning operations, manufacturing operations and the like.

The invention will be further described with respect to the followingExamples which are not meant to limit the invention, but rather tofurther illustrate a few of the various embodiments.

EXAMPLES

Laboratory sand pack tests (20/40 mesh or 850/425 micron) with andwithout nanoparticles treatment show that nanoparticle-treated sandpacks may capture and hold tiny particles that cloud a simulatedwastewater. A simulated wastewater was prepared with 0.25% by weight(bw) natural bentonite and 0.25% bw illite in water. The graph ofparticle size distribution (PSD) for bentonite is shown in FIG. 6. Thevolume weighted mean size for the bentonite from the PSD analysis wasabout 31.2 microns. A similar PSD analysis for the illite gave a volumeweighted mean size of about 33.0 microns.

COMPARATIVE EXAMPLE 1—A test without a nanoparticle-treated sand packdemonstrates that cloudy water flows into the pack, and essentially thesame cloudy water flows out of the pack. FIG. 1 is a photograph of asand pack test apparatus for a sand pack that is untreated withnanoparticles, showing cloudy fluid simulating waste water at the top ofthe apparatus and essentially the same cloudy fluid flowing from theapparatus at the bottom. FIG. 2 is a more detailed photograph of thecloudy fluid simulating waste water at the top of the sand pack testapparatus of FIG. 1. FIG. 3 is a more detailed photograph of the cloudyfluid having passed through the sand pack test apparatus of FIG. 1showing that the fluid remains cloudy.

INVENTIVE EXAMPLE 2—FIGS. 4 and 5 show that cloudy fluid (simulatedwaste water) at the top of the sand pack flows into the nanoparticlestreated sand pack and clear, clean water flows out of the pack at thebottom (FIG. 5). This means that the tiny impurity particles (bentoniteand illite) in the waste-water are captured in the sand pack by thenanoparticles.

Rev Dust (the mean particle size was about 20 microns and it contained12% quartz, 7% cristobalite, 4% illite, 29% mixed layers, 26% kaolinite,and 22% chlorite) was used as another simulated wastewater for testslike Example 1 and 2. The results are the same as that of bentonite andillite wastewater flowing through the sand pack. These Rev Dustparticles were clearly and easily removed.

The nanoparticles were 35 nm MgO, product #12N-0801 available fromInframat Advanced Materials. The procedure for making thenanoparticles-treated sand pack was as follows:

-   -   1. Mixed the nanoparticles with 99.8 wt % monopropylene glycol        to make 2 pound per gallon (ppg) (0.2 kg/liter) (2 pounds (0.9        kg) nanoparticles in one gallon monopropylene glycol) suspension        (nano-fluid).    -   2. Added 2.5 ml of the nano-fluid from step 1 into 250 grams of        20/40 mesh (850/425 micron) sand in a bottle, and shook the        bottle several minutes to make the sand uniformly coated by the        nano-fluid.    -   3. Poured the treated sand into a one-inch (2.54 cm) inner        diameter (ID) acrylic tube to form the sand pack for testing.

After 90 ml of the particle-containing, highly-concentrated cloudy waterwas passed through the treated sand pack, clean, clear water stillflowed out of the pack.

REGENERATIVE EXAMPLE 3—A process of regenerating the sand or ceramicparticle bed may include using a lightly acidic water to strip thenanoparticles and trapped/fixed sediments, contaminants or impuritiesfrom the bed pack. In one non-restrictive version, the acidic water maybe 1.0% HCl or 2% citric acid in tap water to dose the bed pack. Then,new nanoparticles would be placed back onto the bed pack, again as adose treatment fluid composed of nanoparticles product added to tapwater or glycol or the like to re-coat or re-plate the nanoparticlesonto the bed pack particles or materials. The nanoparticles product maybe a glycol, such as propylene glycol, as mentioned, or a USP ortechnical grade mineral oil slurry product.

The acidic stripping fluid, once it removes the nanoparticles andtrapped/fixated sediments, would need appropriate conditioning and/ordisposal. If the trapped sediments are simply river sediments, like soilparticles, then the acidic waste could simply be neutralized (forinstance with sodium bicarbonate (baking soda) or other commonmaterial), and would then be a non-hazardous material, relatively easyto dispose of. However, if there are heavy metals and the like, forinstance, toxic components to the sediments that were trapped orcaptured (e.g. toxic elements, compounds, contaminated soil particles,etc.) by the fixation of the nanoparticles, then once stripped by theacidic water, the stripping fluid would need appropriate handling,conditioning and/or disposal.

In the foregoing specification, it will be evident that variousmodifications and changes may be made thereto without departing from thebroader spirit or scope of the invention as set forth in the appendedclaims. Accordingly, the specification is to be regarded in anillustrative rather than a restrictive sense. For example, specificcombinations of alkaline earth metal oxides, alkaline earth metalhydroxides, alkali metal oxides, alkali metal hydroxides, transitionmetal oxides, transition metal hydroxides, post-transition metal oxides,post-transition metal hydroxides, piezoelectric crystals, andpyroelectric crystals, of various sizes; brines; base fluids; bed andpack particles (sand, ceramic or glass beads, gravel); coating agents(glycols, alcohols, mineral oils) and other components falling withinthe claimed parameters, but not specifically identified or tried in aparticular composition, are anticipated to be within the scope of thisinvention.

The present invention may suitably comprise, consist or consistessentially of the elements disclosed and may be practiced in theabsence of an element not disclosed.

The words “comprising” and “comprises” as used throughout the claims isto interpreted “including but not limited to”.

What is claimed is:
 1. A method for purifying an aqueous liquidcontaining contaminant particles, the method comprising: contacting saidaqueous liquid containing said contaminant particles with a particlepack comprising substrate particles and comparatively smallerparticulate additives; where the substrate particles are comparativelylarger than the particulate additive and are selected from the groupconsisting of sand, gravel, ceramic beads, glass beads, and combinationsthereof, where the particle pack is at least partially coated with acoating agent comprising a carrier fluid selected from the groupconsisting of alcohol, glycol, polyol, vegetable oil, and combinationsthereof, where the particulate additives have a mean particle size of1000 nm or less and are selected from the group consisting of alkalineearth metal oxides, alkaline earth metal hydroxides, alkali metaloxides, alkali metal hydroxides, transition metal oxides, transitionmetal hydroxides, post-transition metal oxides, post-transition metalhydroxides, piezoelectric crystals, pyroelectric crystals, and mixturesthereof; and attracting said contaminant particles from the aqueousliquid to the particulate additive to purify the aqueous liquid.
 2. Themethod of claim 1 where the alkaline earth metal is selected from thegroup consisting of calcium, strontium, and barium, the alkali metal isselected from the group consisting of lithium, sodium, potassium, thetransition metal is selected from the group consisting of titanium andzinc, and the post-transition metal is aluminum, and mixtures thereof.3. The method of claim 1 where the effective amount of the particulateadditives ranges from about 1 part by weight particulate additive forabout 200 to about 5000 parts by weight of the particle pack.
 4. Themethod of claim 1 where the mean particle size of the particulateadditives is from about 4 nm to about 500 nm.
 5. The method of claim 1where the mean particle size of the substrate particles in the particlepack ranges from about 2000 microns to about 45 microns.
 6. A method forpurifying aqueous fluids containing contaminant particles, the methodcomprising: contacting said aqueous liquid containing said contaminantparticles with a particle pack comprising substrate particles andcomparatively smaller particulate additives; where the substrateparticles are comparatively larger than the particulate additive, have amean particle size of from about 2000 microns to about 45 microns andare selected from the group consisting of sand, gravel, ceramic beads,glass beads, and combinations thereof, where the particle pack is atleast partially coated with a coating agent comprising a carrier fluidselected from the group consisting of alcohol, glycol, polyol, vegetableoil, and combinations thereof, where the particulate additives have amean particle size of 1000 nm or less and are selected from the groupconsisting of alkaline earth metal oxides, alkaline earth metalhydroxides, alkali metal oxides, alkali metal hydroxides, transitionmetal oxides, transition metal hydroxides, post-transition metal oxides,post-transition metal hydroxides, piezoelectric crystals, pyroelectriccrystals, and mixtures thereof; where the particulate additive rangesfrom about 1 part by weight for about 200 to about 5000 parts by weightof the particle pack; and attracting said contaminant particles from theaqueous liquid to the particulate additive to purify the aqueous liquid.7. The method of claim 6 where the alkaline earth metal is selected fromthe group consisting of calcium, strontium, and barium, the alkali metalis selected from the group consisting of lithium, sodium, potassium, thetransition metal is selected from the group consisting of titanium andzinc, and the post-transition metal is aluminum, and mixtures thereof.8. The method of claim 6 where the mean particle size of the particulateadditives is from about 4 nm to about 500 nm.
 9. The method of claim 6where the mean particle size of the substrate particles in the particlepack ranges from about 2000 microns to about 45 microns.
 10. A methodfor purifying an aqueous liquid containing contaminant particles, themethod comprising: contacting said aqueous liquid containing saidcontaminant particles with a particle pack comprising substrateparticles and comparatively smaller particulate additives; where thesubstrate particles are comparatively larger than the particulateadditive and are selected from the group consisting of sand, gravel,ceramic beads, glass beads, and combinations thereof where the particlepack is at least partially coated with a coating agent comprising anoil-wetting surfactant, where the particulate additives are of smallermean particle size than the substrate particles, where the particulateadditives are at least partially coated on the substrate particles bythe coating agent, and where the particulate additives have a meanparticle size of 1000 nm or less and are selected from the groupconsisting of alkaline earth metal oxides, alkaline earth metalhydroxides, alkali metal oxides, alkali metal hydroxides, transitionmetal oxides, transition metal hydroxides, post-transition metal oxides,post-transition metal hydroxides, piezoelectric crystals, pyroelectriccrystals, and mixtures thereof; and attracting said contaminantparticles from the aqueous liquid to the particulate additive to purifythe aqueous liquid.
 11. The method of claim 10 where the alkaline earthmetal is selected from the group consisting of calcium, strontium, andbarium, the alkali metal is selected from the group consisting oflithium, sodium, potassium, the transition metal is selected from thegroup consisting of titanium and zinc, and the post-transition metal isaluminum, and mixtures thereof.
 12. The method of claim 10 where theeffective amount of the particulate additives ranges from about 1 partby weight particulate additive for about 200 to about 5000 parts byweight of the particle pack.
 13. The method of claim 10 where the meanparticle size of the particulate additives is from about 4 nm to about500 nm.
 14. The method of claim 10 where the mean particle size of thesubstrate particles in the particle pack ranges from about 2000 micronsto about 45 microns.